<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <script>
      'use strict';
      function f() {
        console.log(this);
      }
      let user = {
        g: f.bind(null),
        // g: f,
      };
      user.g(); //null
    </script>
  </body>
</html>
